1. Field of the Invention
The invention relates to an adjustable drive for axially reciprocating the distributing rollers of at least one inking unit of a printing unit of a rotary printing press, the drive being adjustable to change the amount of axial travel of the distributing rollers.
2. Description of the Related Art
In offset printing presses, it has proven desirable to axially reciprocate the ink distributing rollers in order to more uniformly transfer ink to the ink applicator rollers.
A drive for axially reciprocating the ink distributing rollers is disclosed in U.S. Pat. No. 1,741,414. A disadvantage with that mechanism is that the distributing rollers are driven by an elaborate separate drive for the adjustable axial reciprocation and it is impossible to adjust the phase of the axial reciprocation with respect to the phase of rotation of the plate cylinder. Another elaborate drive of this kind which further permits adjustment when the press is running is disclosed in U.S. Pat. No. 4,513,662.
European Patent No. 66,114 discloses a drive wherein a common eccentric drive whose reciprocating throw is adjustable is provided for two inking units of a four-cylinder printing unit and is disposed on a drive shaft whose movement is derived from an inking unit drive. A disadvantage with that mechanism is that the nature of the coupling makes it impossible to have a separate central adjustment of the axial reciprocation of the ink distributing rollers in the inking units. Difficulties therefore arise, more particularly when in addition to separate central adjustment of the extent or throw of the reciprocation, an adjustment of the phase of the reciprocating movement is also required in order to be able to set up such comparability of the ink surfaces or ink films to be distributed as will satisfy the separate requirements in the two inking units. Another disadvantage is that the common eccentric drive requires a reduction transmission having a driving gear which must be driven by the machine by way of a clutched gear.